Big Bang created everything. Or did it? Physicists propose a second ‘Dark Big Bang’

Dark matter — an invisible entity that makes up much of the universe — has long been one of the most puzzling subjects for astrophysicists.

The term was coined by a Swiss astronomer in 1933 to describe hidden matter that appeared responsible for the peculiar movement of celestial bodies. Since then, scientists have disagreed on the properties and origins of the mysterious element.

“We don’t know what it is. It’s a 90-year-old problem,” Katherine Freese, the director of the Weinberg Institute for Theoretical Physics at the University of Texas at Austin, told McClatchy News.

But a new theory, posited by Freese and her colleague, Martin Wolfgang Winkler, aims to explain where dark matter came from. In a study published in February, the pair hypothesized that a second big bang — a “Dark Big Bang” — brought dark matter into existence.

“People generally assume that (the Big Bang) created everything, but we realized we don’t have any evidence for the creation of dark matter,” Freese said. “Instead of just assuming everything is created at once, we wanted to investigate; can we have this second Big Bang? And the answer is yes.”

Their pioneering theory proposes that dark and visible matter are in fact “completely decoupled” aside from their connection through gravity.

The theory is born out of a fundamental discrepancy between dark matter and other elements in the universe: Dark matter is significantly younger than the other particles, including photons and quarks, meaning its genesis may have come after the Big Bang.

So, Freese and Winkler set out to determine just how late the Dark Big Bang could have taken place. Their conclusion? About 30 days could have passed between the Big Bang and the Dark Big Bang.

“When we talk about the universe we’re usually talking about fractions of a nanosecond or billions of years,” Freese said. “The timescale here is about a month, which is an interesting, human time scale.”

A month does not sound particularly long given the vastness of time, but it’s actually quite a significant delay, the authors write.

“We’re able to study the universe up to three minutes after the Big Bang and absolutely nail it,” Freese said. “I guess what I’m getting at is one month in that sense is quite late.”

This “alternative cosmology,” which calls into question conventional wisdom on the birth of the cosmos, could be bolstered in the future by the detection of gravitational waves, which are created when any matter moves. These waves were first detected in 2015 when two black holes merged, Freese said.

The hope is that gravitational waves with a distinct frequency potentially associated with the Dark Big Bang can be picked up by wave detectors.

This story was originally published March 24, 2023 at 7:17 PM with the headline "Big Bang created everything. Or did it? Physicists propose a second ‘Dark Big Bang’."